A hybrid codec has the advantages of both an audio codec and a speech codec. The hybrid codec can code a sound signal that is a mixture of content mainly including a speech signal and content mainly including an audio signal, by switching between the audio codec and the speech codec. With this switching, coding is performed according to a coding method suitable for each type of content. Thus, the hybrid codec implements a stable compression coding for a sound signal at a low bit rate.
Moreover, it is known that the hybrid codec generates an aliasing cancellation (AC) signal at the encoder side in order to reduce aliasing caused in the case of codec switching.